1. Field
Embodiments relate to a polymer membrane composition for a fuel cell, a polymer membrane prepared therefrom, a membrane-electrode assembly (MEA), a fuel cell including the same, and associated methods.
2. Description of the Related Art
A fuel cell is a power generation system for producing electrical energy through, e.g., an electrochemical redox reaction of hydrogen and oxygen from a hydrocarbon-based material, e.g., methanol, ethanol, and/or natural gas.
Fuel cells are a clean energy source that may replace a fossil fuel. A fuel cell may include a stack composed of unit cells and may have an advantage of producing power in various ranges. Since fuel cells may have four to ten times higher energy density than a small lithium battery, may not release NOx or CO2, and may not be noisy, fuel cells have been highlighted as a next generation energy converter.
A fuel cell may include, e.g., a polymer electrolyte membrane fuel cell (PEMFC) and a direct oxidation fuel cell (DOFC). A direct oxidation fuel cell that uses methanol as a fuel is called a direct methanol fuel cell (DMFC).
The polymer electrolyte membrane fuel cell may have an advantage of having high energy density and power. However, the polymer electrolyte membrane fuel cell may also require careful handling of hydrogen gas and accessory facilities, e.g., a fuel-reforming processor for reforming a fuel gas such as methane, methanol, and natural gas, in order to produce hydrogen.
The direct oxidation fuel cell may have a lower energy density than the polymer electrolyte membrane fuel cell. However, the direct oxidation fuel cell may have an advantage of easy handling of a liquid-type fuel, a low operation temperature, and no additional fuel-reforming processor.
In the direct oxidation fuel cell, a stack that actually generates electricity may include several to scores of unit cells stacked in multi-layers. Each unit cell may be made up of a membrane-electrode assembly (MEA) and a separator (also referred to as a bipolar plate). The MEA may include an anode (referred to as a fuel electrode or an oxidation electrode) and a cathode (referred to as an air electrode or a reduction electrode) attached to each other with an electrolyte membrane therebetween.
A fuel may be supplied to an anode and adsorbed on catalysts of the anode and then oxidized to produce protons and electrons. The electrons may be transferred into a cathode via an external circuit and the protons may be transferred into the cathode through the polymer electrolyte membrane. In addition, an oxidant may be supplied to the cathode. Then, the oxidant, protons, and electrons may be reacted on catalysts of the cathode to produce electricity along with water.